Cathode ray tube having a plurality of interchangeable cathodes



'Nov. 5, 1963 K. J. BURNETT 3,109,953

CATHODE RAY TUBE HAVING A PLURALITY OF INTERCHANGEABLE CATHODES FiledSept. 28, 1960 2 Sheets-Sheet l INVENTORZ KENNETH J. BURNETT,

I IS ATTORNEY.

Nov. 5,1963 K. J. BURNETT 3,109,953

CATHODE RAY TUBE HAVING A PLURALITY OF INTERCHANGEABLE CATHODES FiledSept. 28. 1960 2 Sheets-Sheet 2 KENNETH J.BURNETT,

United States Patent O Sir-39,953 CATHOBE MY TUBE HAVING A PLURAHTY G75INTERCHANGEAELE CATHODE Kenneth J. Burnett, Liverpool, N.Y., assignor toGeneral Electric Compmy, a corporation of New York Filed Sept. 23, 195igar. No. 59,679 6 lairns. (til. 313236) The present invention relates toa cathode ray tube incorporating a plurality of interchangeable cathodesand means for changing these cathodes so that as used out, difierentcathodes are aligned with the grid and anode in operative relationshipwithin the tube. More particularly the invention relates to switchingcathodes in a cathode ray tube wherein deterioration requires aplurality of alternate cathodes by a device enabling quick changing ofthese cathodes.

The invention is useful where impurity is required within the tube andwhere tubes at relatively low vacuum pressures are required. Suchrequirements occur in electron microscopes, in optical light valveprojection sys tems, in electron tape Writing devices employing electronbeam writing; and also in fluorescent, phosphorescent, and directviewing and evaluating tubes. Often in such tubes an impurity must beintroduced. This extra impurity introduced to the cathode causes rapiddeterioration of the cathode. It is applicable also where long andintensive use deteriorates the cathode.

The invention is useful further for applications such as public displayor military use where it is essential that the device be 100% operativewhen needed. For such uses in the event of failure due to cathodedeterioration, time cannot be spent to demount a tube and substituteanother in its place. In public viewing or in other uses requiringurgent display the facilities may not be readily available. Also, it isnot practical to change the tube under such conditions. For such uses,without the invention it might be required that two complete systems becontinuously available because of embarassment of inability for displaywhen necessary. The present invention solves the problem in that itremoves the most frequent cause of deterioration and breakdown, namely,the deterioration of cathodes. Two complete systems, one a standby, areno longer as necessary, and reliablity is increased.

The prior art does not provide multiple cathodes in a cathode ray tubewith means for their ready interchange upon deterioration of a cathode.

The prior art device of G. l. Hooper, Patent No. 2,740,- 916, issuedApril 3, 1956, for Vacuum Tube With Replacement Filaments shows aseparate vacuum enclosure which houses a filament only, and which can beinserted without losing the vacuum in the envelope itself. This devicepermits changing of the filament only.

The Cathode Ray Oscilloscope of Patent No. 2,175,- 582 to Vogel et 211.,issued October 10, 1939, provides a disk cathode which can be rotatedwhere a particular emission spot appears on the disk. This permitsadjustment for evenness of emission from the different portions of thecathode.

The present invention improves tubes such as cathode ray tubes in thatit provides a plurality of interchangeable cathodes and hence permitssubstantially continuous operation of equipment. It also enablesadjustment of positioning and use of hairpin cathodes. It providesfeatures of replacement and adjustment of lateral positioning foralignment with the grid and anode of the tube.

Accordingly, an object of the present invention is to provide apparatusfor changing cathodes in cathode ray tubes without losing the vacuum andwhereby elimination of appreciable shutdown time for such changes iseffected.

Bifibfi Patented Nov. 5, 1963 Another object of the invention is toprovide substantially continuous display where required such as formilitary and public entertainment without necessity for substantialstandby equipment in addition to the operating equipment.

Another object of the present invention is to provide a means forchanging cathodes in a cathode ray tube to permit substantiallycontinuous operation and which means is adapted for various kinds ofcathodes including point source emitters such as of the hairpin tungstenfilament type.

While the novel and distinctive features of the invention areparticularly pointed out in the appended claims, a more expositorytreatment of the invention, in principle and in detail, together withadditional objects and ad vantages thereof is afforded by the followingdescription and accompanying drawing in which:

FIG. 1 is a cross-sectional view of a tube incorporating a rotatableturret holder arrangement for demountable cathodes illustrative of apreferred embodiment of the present invention;

FIG. 2 is an isometric partially cut-away view illus trative of detailsof features of the interior mechanism and adjustment means of thepreferred embodiment of FIG. 1;

FIG. 3 is a detail view illustrating insulating type adjustment meanswhereby fine positioning of the cathode to laterally align it with thegrid and anode may be made upon rotation of the turret on which thecathodes are mounted;

FIG. 4 is a sectional view of a form of indirectly heated cathodemountable in the turret of the FIG. 1 embodiment; and

FIG. 5 is a side elevational view of a hairpin tungsten filament pointsource emitter mountable in the turret of the FIG. 1 embodiment.

Referring to the drawings and in particular to FIG. 1, a demountablecathode ray tube generally designated 10 is mounted on a supportingstand 11. The tube 11} comprises an anode 13, a control electrode 50 anda cathode assembly 66*.

Anode 13 is of elongated generally cylindrical shape and has an anodetip 12. The anode end portion including tip end 12 and the oppositeanode end are attached to anode 13 by means such as screws (notnumbered).

The cathode assembly 60 comprises a ribbed, apertured, inversecup-shaped member 72, a turret assembly 20, a spring retaining ring 83'and a cover member 84. The open end of cup member 72 faces the grid 50.The top end of the inverse cup-shaped member 72 comprises aperturedturret support end wall 25. Disposed in the central aperture 110 ofturret support 25 is a turret ring member having a flange or boss 26.Ring 90 comprises the rotatable ring of the turret. Ring 90 iscounterbored from the end opposite the flange 26 end to define a tipturret plate retaining portion 80. An insulating plate member 21 and afeedthrough insulator member 55 superimposed on member 21 in adjacentrelationship provide cathode retaining means. Insulating plate 21 is ofsize to be received by the counterbored portion of member 26 in bearingrelationship, and is seated on the inner surface of turret retaining tip8%. Feedthrough insulating member 55 is of slightly reduced diameterwith respect to member 21.

Protr-uding through the feedthrough insulator 55 and support plate 21are the cathode support rods 22 of a plurality of cathodes 56 (see FIG.5). The cathodes 56 are disposed in circular array under plate 21 in aring of lesser diameter than plate 21. The plate 21 and the feedthroughmember 55 are axially aligned with the axis of turret 20 and they areeccentric with respect to the axis of the grid 50 and the anode 13. Thedisplacement in axes of grid 58 and anode 13 and of members 55 and 21 isthe radius of the circular array of cathodes 56 so that upon rotation ofturret 20 and hence of the plate 21 and feedthrough 55 about theircentral axis the cathodes 56 are in turn disposed in alignedrelationship with the central axis of the grid 50 and the anode member13.

The turret end wall 25 of the cathode assembly cup 72 supports theturret 2t Rotating turret 24 comprises also flange 26, the feedthroughplate 55, a turret gear 31 and cathode mounts 22. The turret gear 3-1 isattached to the turret 2t by fastening means, for example, screws (notnumbered). The upper surface of gear plate 31 contains a plurality ofgrooves (not numbered) indented therein in circular array.

Secured to the cylindrical ribbed cathode assembly cup member 72 is aspring retaining ring member 83 which is suitably fastened to the wallof cathode assembly cup 72. Ring 83 has an aperture therethrough alignedwith the apenture in turret ring 9%.

A cover member '84 is superimposed adjacent the ring 83 by fasteningmeans (not numbered). The cover member 84 supports a block member 86 towhich are attached a pair of terminals 87 (see FIG. and a pair ofcontact fingers 12%. Contact fingers 129 are flat spring conductorsyieldably engaging the respective anode aligned cathode support rods 22.A cathode 56 is suspended from each pair of support rods 22. Covermember 84' is suitably apertured to permit protrusion of the contactfingers 12f} therethrough to make contact with successive IGSPC tivecathode suppont members 2-2., as members 212 are rotated into positionopposite the grid 88 and anode tip 12. In this manner a single pair ofcontact arms 12?; successively engages the cathode support rods 2-2 ofsuccessive cathodes 56.

The ball member 30 is successively locked into the plurality of :detentgrooves or slots 13% of gear plate 31 upon indexing the turret 26*". Theball member 36 is yieldingly urged against the respective detent lSll'of the plate member 31 with which it is aligned at the time by springmember 29. An indexing pin 23 is attached to spring 2%.

Upon lifting of indexing pin 28, spring member 2-? to which it isattached, is lifted also. This permits the ball 3%) to rise uponindexing of the turret plate 31 to bring the next successive cathode 56in line with the anode tip 12.

A neoprene O-ring 23 is set into a recess 24 of turret support 25.Neoprene Oring 23 provides vacuum seal and also yieldingly and bearinglyretains the outer flange surface portion of the turret member 20 inslidable relationship to provide a proper surface for rotationtherearound.

The control grid 58 comprises a generally cylindrical grid support body52, a grid portion 88 and a lower increased diameter annular portion 89.The grid portion 88 of the control grid assembly 50 is disposed normalto the axis of the anode and cathode and has a central aperture alignedwith the axis of the anode 13.

Attached underneath and adjacent to control electrode support body 52 isa plate 131 which with a recess counterbored in the enlarged end 9:22 ofcontrol electrode body 52 forms a recess pocket to contain a neoprenedeformable O-ring 51 between the separating insulator ring 136 disposedexternally of and spaced from anode 13 and body 52.. of controlelectrode 50. Separating ring 136 is in turn supported around anode 13by ring member 137 and anode flange 94. Deformable O-ring 98 is disposedin the recess formed by anode flange 94, separating ring 136 and ring'95.

Thus, the anode member 13, the control grid assembly 59 and the cathodeassembly 60 are separated and positioned with respect to one another. Aplurality of neuprene O-rings are provided which fit into receses inthese members. For example, separating the turret support member 25 andthe turret 20 is deformable O-ring member 23. Disposed between thecontrol electrode assembly 5% and the cathode asesmbly 72 in a recess(not nut bored) in the cathode assembly is an O-ring 16. Disposedbetween insulator 136 and a recess in the control electrode assembly 58is a deformable O-ring 51. Disposed in a recess formed between theflange 94, insulator 136 and hold down ring $5 is a deformable O-ring93. Disposed between the supporting stand 11 and a recess in the anode13 is a deformable O-ring 1.5. The O-rings l5, i6, 23, 51 and 98 arevacuum sefls for the cathode ray tube 1! The control grid 5% is furtherheld in fixed position by screw means (not numbered) which screw gridflange member 92- to anode connected flange member 93. Ring $3 issupported on the surface of support 11.

A plurality of alignment adjusting members 40 (see FIG. 3) are provided.Each has a fingerhold knurled portion 4 3, a threaded shaft or screwportion 42, an internally threaded insulating rod member 162, a lockingnut 4'1 and a threaded seating member N91.

The spacing portion of the plurality of adjusting members are disposedbetween the underface or" the flange 166 of the cathode structure 72 andthe ring 96 surrounding the anode structure 13 in order to provideadjustability for alignment and spacing of the cathode with respect tothe grid and anode for initial setting and on turret rota tion. Aportion of threaded shaft 4-2 extends through and terminates in knurledfingerhold 43 underneath ring )3. The spacing and alignment isparticularly important for hairpin tungsten filament type cathodes asshown in FIGS. 1 and 5. t of the hairpin tungsten filament requiresexaet positioning. Transverse motion of the entire cathode assembly andturret holding unit is provided by the adjusting means dill.

Referring particularly to FIGS. 2. and 3 the hemisphereshaped seat 191is seated in recess 4'4 in the cathode assembly flange member 161%Adjusting means 49 provides an insulating rod 1&2. In rod 16-2 arethreaded end counterbores (not numbered). Seat member 1131 is threadedlyfastened axially into one counterbored end at rod 1%2. Screw shaft 42 isfastened into its other threaded counterbored end. Lock nut 41 holds thethreaded shaft 42 attached fixedly into rod 16-2. An aperture 16-4 inflange 93 is threaded to receive screw member 42 in threadedlyadjustable engaging relationship. Member 42 is threaded substantiallyalong its length. Upon rotation of knurled member 4-3 thread 42 isretracted from or inserted further through aperture 164 to adjustspacing of the cathode elements 56 (or cathodes 564 as in the FIG. 4embodiment) with respect to the anode 13. Hemisphere-shaped member 1&1is bearingly e pe thrust within recess 44 against the underside offlange member 16%). Upon rotation of knurled knob 43 and of the threadportion 42 within the corresponding threaded aperture 164 of anode ribmember 93 through which it extends the rib member 169 is caused to bedisplaced with respect to the anode rib or flange member 95 and itsattached anode. This causes the cathode assembly on and hence thecathode holding turret 2i) and thus the cathode 56 to become laterallydisplaced with respect to the anode 13.

A turret rotating means 195 is provided comprising a shaft 167terminating in a gear 1.6%. Gear 1%? is positioned and sized to matewith and drive turret gear 31 to rotate turret 26 upon indexing tochange cathodes. Shaft 107 extends through and is aligned by apertures(not numbered) in cathode flange 169 and an eccentric flange port-ion161 of cathode assembly 60. The lower portion of shaft comprises asleeve 16%, a knurled fingerhold 106 to rotate shaft Hi7 and a locknut141 to secure sleeve 10% in locked position against the shaft portion107. Hence, by rotating fingerhold means 1% the turret 2G may be made tonotate to desired cathode position. Sleeve 108 of shaft N5 is disposedwithin a substantially semicircular goo-ye extending into an edge sector3,1 of ring 93 and aligned with the cathode flange lot and cathodeeccentric flange portion 161 apertures.

The invention thus provides a display tube in which electron emittingcathodes may be interchanged with m nimum interruption to operation Uponrotating to inder-i the turret which contains a circular array ofcathodes, the are successively brought into position opposite the gridand anode. Detent releasable locking means are provided to lock eachsuccessive cathode in place as the previous one is replaced. Upon suchindexing to rotate the turret a new cathode is inserted opposite anode13 as n eded so that tube operation is continued despite destr ction ordeterioration to the former current emitter or cathodes utilized.

in the case of an indirectly heated cathode fine adjustability is notcritical (see FIG. 4-). lo-wever, for a point source emitter such as thehairpin tungsten filament of FIG. 5 exact positioning must be obtained.Lateral alignment means for optimum position for emission of the cathode56 to a position opposite the anode 13 is provided.

This is accomplished by means of the cathode position adjustment members4 3. Members are adjusted by threadedly advancing or retarding screwmembers 4-2 by grasping and hand turning fingerhold This causes theseating members 44 disposed in recess ltll to displace the turretassembly 23 with respect to the anode by sliding the O-ring 16 alonggrid support body 52 in accordance with the adjustment of the adjustablemeans 49. This effect tilts cathode assembly 6%) with respect to gridsupport 56, thus causing l teral displacement the small amount necessaryto align the cathode 55 for optimum emission of electron energ towardthe anode 13.

Turning the fingerho-ld 3-3 rotates the screw 42 of cathode portionadjustment means 49. Displacement of the cathode body member 72 followsby urging the eagainst to a corresponding degree the adjustment memberin recess 44 to cause cocking of the structure. This is permitted by theslidably bearing, deformable O-ring 145. This provides adjustment forfine alignment. The plurality of adjustment members do are disposed incircular array through the ring for cocking the cathode assembly withrespect to the grid and anode to effect lateral displacement in therequired direction.

Upon indexing the turret to successive positions ball 3% falls into thesuccessive detent receiving groove means 136 Where it locks sequentialcathodes into operative position.

Various modifications of the invention are contemplated as Within itsscope. For example, in one embodiment of the invention contemplated andput into practice the turret was disposed in angular position withrespect to th remaining body and the turret axis of the anode.

While a specific embodiment of the invention has been shown anddescribed, it should be recognized that the invention should not belimited thereto. It is accordingly intended in the appended claims toclaim all such variations as fall within the true spirit of theinvention.

What is claimed is:

1. A cathode ray tube comprising an anode and a control electrodepositioned in aligned relationship, a turret structure for supporting aplurality of spaced cathodes arranged in a ring such that successivecathodes are movable to aligned relationship with said anode and saidcontrol electrode, a turret retaining body member for rotatablysupporting said turret, a vacuum seal means set between said body memberand said turret for vacuum onclosing said anode, cathodes and controlelectrode and cases 5 providing a slidable bearing for rotation of saidturret, and means to rotate said turret so as to successively posisaidcathodes in alignment with said anode and said control electrode.

2. The apparatus of claim '1 including fine adjustment means to adjustsaid cathodes laterally with respect to said anode to causesubstantially optimum ali nment and optimum cathode to cont ol electrodespacing.

3. The apparatus of claim 2 wherein said adjustment means composes aplurality of shaft members, each shaft member comprising a screw member,an insulating rod and a seat member in ali ned fastened togetherrelationship, a pair of annular rings fixed to each of said anode andsaid turret retaining body respectively, one of said annular ringshaving a plurality of groove seats formed therein, an end of the seatmember of each of said shaft members being seated in one of said grooveseats, control electrode support means, said control electrode supportmeans and said turret retaining body having a recess therebetwcen, adeformable bearingly slidable O-ring disposed in said recess, the otherof said annular rings having a plurality of threaded aperturestheretbrough dimensioned to receive said shaft screw members in threadedrelationship, said shaft members being turned to longitudinally displacesaid O-ring to change the position of said turret hence its alignedcathode with respect to said anode.

4. A cathode ray tube comprising an anode, a turret retaining bodymember, a turret, means to support a circular array of spaced cathodesin said turret, O-ring means disposed between said body member and saidturret such that said turret is rotated bearingly against said O-ringmeans, said O-ring means maintaining a vacuum sealed relationshipbetween said body member and said turret, said turret being mounted onan axis parallel to and eccentric to the axis of said anode, thedistance between anode and turret axes being the radius of the circle ofsaid cathode array so that upon rotation of said turret successivecathodes are aligned with said anode, and means to fixedly retain saidturret member in successive cathode-anode aligned positions.

5. The apparatus of claim 4 including means to effect lateraldisplacement of said turret with respect to said anode such as toprovide fine adjustment and to enable optimum ali nment of each of saidcathode as successively disposed in alignment with said anode withrespect to said anode.

6. The apparatus of claim 5 having tube support means including means tosupport said anode and means to support said turret retaining bodymember and wherein said adjustment means comprises a plurality ofannularly spaced threadedly adjustable shaft members disposed inmoveably threaded engagement wtih said anode support means and inabutting bearing relationship to said body member and including a secondO-ring disposed between said body member and a portion of said tubesupport means such that rotation of said threaded shafts adjusts saidturret with respect to said body member and thereby slides said O-ringin accordance with rotation of said shafts to enable said alignmentwhile retaining vacuum sealed relationship between said body member andsaid tube support means portion.

References tilted in the file of this patent UNITED STATES PATENTS2,324,899 Arthur July 29, 1943

1. A CATHODE RAY TUBE COMPRISING AN ANODE AND A CONTROL ELECTRODEPOSITIONED IN ALIGNED RELATIONSHIP, A TURRET STRUCTURE FOR SUPPORTING APLURALITY OF SPACED CATHODES ARRANGED IN A RING SUCH THAT SUCCESSIVECATHODES ARE MOVABLE TO ALIGNED RELATIONSHIP WITH SAID ANODE AND SAIDCONTROL ELECTRODE, A TURRET RETAINING BODY MEMBER FOR ROTATABLYSUPPORTING SAID TURRET, A VACUUM SEAL MEANS SET BETWEEN SAID BODY MEMBERAND SAID TURRET FOR VACUUM ENCLOSING SAID ANODE, CATHODES AND CONTROLELECTRODE AND PROVIDING A SLIDABLE BEARING FOR ROTATION OF SAID TURRET,AND MEANS TO ROTATE SAID TURRET SO AS TO SUCCESSIVELY POSI-